1. Field of the Invention
The present invention relates to a total heat exchanger which exchanges sensible heat and latent heat, and, more particularly, to improvement in a latent heat exchanging efficiency.
2. Description of the Related Art
A known total heat exchanger is described below.
This heat exchanger, which is of a honeycomb structure, is formed by stacking a corrugated substrate, which serves as a space retaining plate, and a flat substrate, which serves as a partition plate. The corrugated and flat substrates are constructed of an artificial paper including cellulose fibers and thermoplastic fibers, and are bonded with the thermoplastic fibers by performing heating and pressurizing treatments, which also provides rigidity (see, for example, Japanese Unexamined Utility Model Registration Application Publication No. 56-93694 (pages 1 to 4, FIG. 1)). Also, there is a document which describes other related art (see, for example, Japanese Unexamined Patent Application Publication No. 2002-310589 (pages 3 to 5, FIGS. 1 to 4)).
A known heat exchanger has, during the exchange of latent heat, a lower rate of blocking the movement of moisture through a joint,. that is, has less of a reduction in an effective moisture permeable area as compared to a joint bonded with a moisture impermeable adhesive because the corrugated and flat substrates are bonded with the thermoplastic fibers by performing heating and pressurizing treatments. However, the known heat exchanger has an insufficient moisture permeability because both the flat substrate, which serves as a partition, and the corrugated substrate, which serves as a space retaining plate, themselves have a poor moisture permeability.
Referring now to the air conditions in summer and winter for the total heat exchanger (cited from JIS B 8628 air conditions for a total heat exchanger), it is shown that, in summer, an outdoor air temperature and a relative humidity are 35°° C. and 64.4% RH respectively, and a room temperature and a relative humidity are 27° C. and 52.4% RH respectively and, in winter, an outdoor air temperature and a relative humidity are 5° C. and 57.8% RH respectively, and a room temperature and a relative humidity are 20° C. and 51.1% RH respectively. That is to say, under the summer and winter air conditions, the energy proportion of humidity (latent heat) to a total heat is about 50%. Particularly, the energy proportion of latent heat of a room in summer accounts for two-thirds. Therefore, a latent heat exchanging efficiency is important. Furthermore when the humidity becomes higher in summer, the proportion of the latent heat becomes larger, and thus, the latent heat exchanging efficiency is of greater importance.
Recently, there has also been a need for further improvement in heat exchanging efficiency of the total heat exchanger. For further improvement in heat exchanging efficiency, improvement in the latent heat exchanging efficiency is particularly important as described above. However, the known heat exchanger still has the above problems.